MonkeNy, looking at my JTIS CD, it is sounding like you have a shorted out solenoid in the tranny. As for how much it would take to access the solenoid, I can not say. A shop would need to do something like that. The first check that I would tell you to do is to get the front end up in the air so you can access the tranny. From there, you will see a wire bundle coming off. Do a visual of the wiring and see if there is something obvious there. IT is possible something got trapped under the car and damaged the wiring harness, which could lead to this problem.

Because of these two faults, unless the tranny is starting to come apart on the inside, I doubt you can have 2 errors occur at the same time. The 745 code indicates that shift solenoid #1 (affects gears 1, 2, 4, and 5). The code signified that either the solenoid has shorted to ground or has failed open. Code 795 is for shift solenoid #3. This affects gears 1,2, and 3. This code signifies that either the solenoid has shorted to ground or the solenoid has failed open.

I would say to take the car to a local shop, have them drop the pan and see if they can spot anything. But, for the most part, it sounds like it is an electrical issue, not a mechanical issue. A good tranny shop should be able to diagnose an electrical issue dealing with the tranny.